Pass f6 toroidal transformer


Joined 2010
Paid Member
400va could work, right? And 300va. Or is the F6 a special case?

All of the First Watt amps will work perfectly with a 300VA transformer. (Nelson uses 300VA, if it’s good enough for him... :) )

If buying from Antek I strongly recommend a shielded transformer, the AS- series. They are 400VA and smaller.

Over sizing the transformer doesn’t actually do much, but since people like overbuilding the PSU, what the heck, why not. ;)
Joined 2002
Paid Member
1) You need a transformer rated for 220V and giving the proper secondary voltage.
Fuse and inrush thermistor need to be appropriate for your voltage. With that, then
everything should be fine.
2) Indefinitely, if the amp is properly constructed with sufficient heatsinking.
Since you are a new builder let's re-state some of the guidelines.
Buy good components, from mainstream suppliers.
Buying components, especially the transistors from E-bay is likely to result in fake components and failure.
The J-fets (Q3-Q4) are very important, and difficult to find. The store has good quality equivalents in the right grade.
There is a mod to the zenner diodes that makes bias more stable. This is very much worth doing during the build.
See the mods on the circuit below.


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My F6 has a 400va transformer with the store powers supply boards built as standard.
Fitted in a 400u chassis. (Make sure that you get the 10mm front plate.)
Tranny is mounted vertically on an aluminium angle bracket.
Totally silent (mechanical noise and through amp.)

Store's Deluxe 4U comes with 10mm front plate! But do i need to order 21$ rear panel dissipante?